transform-field-names: Skip field if old_field_name == new_field_name

[joverlee521]

Context

Prompted by nextstrain/avian-flu#40 (comment)

The current workaround is to use the --force flag to silence the warnings, but this can result in missing actual field name overwrites.

Description

If the old field name is the same as the new field name, then the script should skip renaming which would skip the loud warning:

ingest/transform-field-names

Lines 35 to 43 in 5b74edc

	for old_field, new_field in field_map.items():
	if record.get(new_field) and not args.force:
	print(
	f"WARNING: skipping rename of {old_field} because record",
	f"already has a field named {new_field}.",
	file=stderr
	)
	continue